<?php

namespace App;

use Movim\Model;

class Cache extends Model
{
    protected $primaryKey = ['user_id', 'name'];

    public $incrementing = false;
    protected $fillable = ['user_id', 'name'];
    private static $instance;

    public static function instanciate()
    {
        if (!is_object(self::$instance)) {
            self::$instance = new Cache;
        }

        return self::$instance;
    }

    /**
     * Helper function to access cache.
     */
    public static function c()
    {
        $cache = self::instanciate();

        return call_user_func_array([$cache, 'handle'], func_get_args());
    }

    /**
     * Fetches or commits an object to cache with the provided key.
     *
     * Prototype: handle(string $key, ...)
     *
     * The following fetches an object from cache.
     *   handle('key')
     *
     * This commits an object to cache.
     *   handle('key', $object);
     *
     * Several objects can be commited to cache in this manner:
     *   handle('key', $object1, $object2, $object3);
     * And retrieved as follows:
     *   list($object1, $object2, $object3) = handle('key');
     */
    public function handle($key)
    {
        $arglist = func_get_args();
        $key = $arglist[0];

        if (func_num_args() == 1) {
            $content = $this->_readCache($key);

            if (isset($content) && $content != '') {
                return $content;
            }

            return null;
        }

        if (func_num_args() == 2) {
            return $this->_writeCache($key, $arglist[1]);
        }
        // Cutting a piece of the args.
        $content = array_slice($arglist, 1);
        return $this->_writeCache($key, $content);
    }

    /**
     * Serializes data in a proper fashion.
     */
    private function _writeCache($key, $object)
    {
        $data = str_replace(
            "'",
            "\\'",
            base64_encode(gzcompress(serialize($object)))
        );

        if (User::me()->id) {
            $cache = Cache::firstOrNew(['user_id' => User::me()->id, 'name' => $key]);
            $cache->data = $data;
            $cache->save();
        }
    }

    /**
     * Unserializes data.
     */
    private function _readCache($key)
    {
        $cache = $this->where('user_id', User::me()->id)
                      ->where('name', $key)
                      ->first();

        if (isset($cache)) {
            return unserialize(
                gzuncompress(base64_decode(str_replace("\\'", "'", $cache->data)))
            );
        }

        return false;
    }
}